Over the past twenty years, water beds have become increasingly popular because of the therapeutic comfort they provide which is not offered in conventional spring mattresses. Original water bed mattresses consisted of a single, large, flexible bladder filled with water or other liquid and supported in a steady support frame. These water beds gained limited popularity because of many disadvantages such as wave motions and continuing oscillating responses to relatively small motions, excess of weight, which made them impossible to move, difficulty in filling and emptying, limited buoyancy adjustments, and leakage problems. When a leak would occur, it would be necessary to empty the mattress completely, patch the mattress and then refill it. In addition, the amount of water involved in such a leak could result in substantial water damage to the surroundings, and would be extremely difficult to clean up. In response to the problems of excessive wave motion and oscillations of the conventional water bed mattresses, numerous mattresses were developed which incorporated complicated baffle structures or other motion dampening systems for reducing the wave action. However, although the complicated baffle constructions diminished the problem of excessive wave motion, they did nothing to alleviate the problems of weight and leakage. In fact, the baffles tended to increase the weight of the water bed mattress as well as add to the cost and complexity of manufacturing.
Water bed mattresses have been designed in an attempt to solve the weight and leakage problems, as well as the problem of wave motion. These mattresses comprise a plurality of individual tubes supported in a cavity defined by pairs of foam panel members, or a plastic tray structure. The individual tubes do not transmit significant side forces or wave motion to the other tubes, and thus provide a steadier sleeping surface than the conventional single bladder mattress. In addition, the individual tubes can be removed from the bed for relatively easy filling and drainage, and can be filled to varying degrees to control the firmness of the mattress. When a leakage occurs, it is necessary only to repair or replace a single leaking tube, rather than to remove an entire bladder for patching. The tube configuration also reduces the weight of the mattress.
Although the tube type water bed has some advantages, it still suffers from several drawbacks. First of all, although the tubes do not transmit side forces to one another, waves are still free to travel longitudinally from one end of the tube to the other. Thus, some oscillating motion is still felt. In addition, the individual tubes are designed to hold approximately fifty pounds of water. Although lighter than the conventional water beds, they still are heavier than desireable for the average consumer. Furthermore, the foam panel members or tray structure which contains the tubes allow for any leakage to spread out over the entire surface of the panel or tray. Although the amount of water involved in the leak would be less, and it is contained within the foam panel or tray, the entire bed would need to be disassembled to clean up the leak. As a further problem of the tube type mattress, the lack of fluid communication between the individual tubes produces poor heat transfer between tubes. Thus, a conventional water bed heating unit consisting of a single heating pad placed under the center of the mattress will not satisfactorily heat those tubes which are located farthest from the center. Finally, although the tube configuration allows the firmness of each side of the water bed to be varied, the firmness between the top and the bottom of the water bed cannot be controlled.
Thus, there has existed a long felt need in the art for a new and improved water bed mattress which reduces wave motion, is easy to transport and fill, minimizes leakage, and provides a means for adjusting the firmness of the bed at any point along the surface.